libgui: Improved window refresh and GUI app event loop

Window refresh is now the primary trigger for GUI app event loop
iteration. The event loop uses a timer for low-frequency non-visual
updates.

GLWindow keeps refreshing itself as quickly as possible.

doomsday/libs/appfw/include/de/framework/basewindow.h

@@ -77,7 +77,7 @@ class LIBAPPFW_PUBLIC BaseWindow : public LIBAPPFW_BASEWINDOW_SUPER
     /**
      * Request drawing the contents of the window as soon as possible.
      */
-    virtual void requestDraw();
+//    virtual void requestDraw();
 
     void draw() override;
 
@@ -93,14 +93,14 @@ class LIBAPPFW_PUBLIC BaseWindow : public LIBAPPFW_BASEWINDOW_SUPER
 #endif
 
 protected:
-    /**
+    /*
      * Called when a draw request has been received. This method should carry out any
      * preparations necessary before the frame can be drawn. It can also cancel the
      * frame is needed.
      *
      * @return @c true to continue drawing the frame, @c false to abort the frame.
      */
-    virtual bool prepareForDraw();
+//    virtual bool prepareForDraw();
 
     virtual void preDraw();
     virtual void postDraw();

doomsday/libs/appfw/src/basewindow.cpp

@@ -122,6 +122,7 @@ WindowTransform &BaseWindow::transform()
     return *d->xf;
 }
 
+#if 0
 bool BaseWindow::prepareForDraw()
 {
     if (isGLReady())
@@ -144,23 +145,8 @@ void BaseWindow::requestDraw()
         // Not right now, please.
         return;
     }
-
-    // Initialize Oculus Rift if needed.
-    auto &vr = DE_BASE_GUI_APP->vr();
-    if (vr.mode() == VRConfig::OculusRift)
-    {
-        if (isGLReady())
-        {
-            makeCurrent();
-            vr.oculusRift().init();
-        }
-    }
-    else
-    {
-        makeCurrent();
-        vr.oculusRift().deinit();
-    }
 }
+#endif
 
 void BaseWindow::draw()
 {
@@ -172,9 +158,21 @@ void BaseWindow::draw()
 void BaseWindow::preDraw()
 {
     auto &vr = DE_BASE_GUI_APP->vr();
+
+    // Initialize Oculus Rift if needed.
     if (vr.mode() == VRConfig::OculusRift)
     {
-        vr.oculusRift().beginFrame();
+        if (isGLReady())
+        {
+            makeCurrent();
+            vr.oculusRift().init();
+            vr.oculusRift().beginFrame();
+        }
+    }
+    else
+    {
+        makeCurrent();
+        vr.oculusRift().deinit();
     }
 }
 

doomsday/libs/appfw/src/guirootwidget.cpp

@@ -437,7 +437,7 @@ void GuiRootWidget::update()
     }
 
     // Request a window draw so that the updated content becomes visible.
-    window().as<BaseWindow>().requestDraw();
+//    window().as<BaseWindow>().requestDraw();
 }
 
 void GuiRootWidget::draw()

doomsday/libs/gui/include/de/gui/glwindow.h

@@ -157,6 +157,8 @@ class LIBGUI_PUBLIC GLWindow : public Asset
      */
     bool ownsEventHandler(WindowEventHandler *handler) const;
 
+    void checkNativeEvents();
+
     enum GrabMode { GrabNormal, GrabHalfSized };
 
     /**
@@ -210,8 +212,6 @@ class LIBGUI_PUBLIC GLWindow : public Asset
 
     virtual void draw() = 0;
 
-    void handleSDLEvent(const void *);
-
 public:
     static bool mainExists();
     static GLWindow &main();

doomsday/libs/gui/include/de/gui/guiapp.h

@@ -51,7 +51,6 @@ class Thread;
  * @ingroup gui
  */
 class LIBGUI_PUBLIC GuiApp : public App
-                           , DE_OBSERVES(Loop, Iteration)
 {
 public:
     enum MouseCursor { None, Arrow, ResizeHorizontal, ResizeVertical };
@@ -103,9 +102,6 @@ class LIBGUI_PUBLIC GuiApp : public App
 protected:
     NativePath appDataPath() const override;
 
-    // Observes Loop iteration.
-    void loopIteration() override;
-
 private:
     DE_PRIVATE(d)
 };

doomsday/libs/gui/include/de/gui/guiloop.h

@@ -26,7 +26,7 @@ namespace de {
 class GLWindow;
 
 /**
- * Continually triggered loop that activates a window when triggering iterations.
+ * Loop that gets triggered after each time GLWindow contents have been refreshed.
  */
 class GuiLoop : public Loop
 {